Re: this is getting crazy

John Larkin wrote: 
On Tue, 16 Aug 2005 08:50:33 +1200, Terry Given <my_name@xxxxxxxx>
wrote:


John Larkin wrote:

On Sat, 13 Aug 2005 13:05:37 +1200, Terry Given <my_name@xxxxxxxx>
wrote:



Kia Ora Joerg,

Joerg wrote:


Hello Terry,



Size Of board                   16.41 x 11.148 sq in
Equivalent 14 pin components    0.58 sq in/14 pin component
Components on board             1335


Man, you guys do large boards. A couple of minutes ago I checked off on the Gerbers of my last one. Under 200 parts :-(

I saw the costed BOM for that PCB yesterday. total parts cost (excl. 121 LEDs) is $8 less than the micro cost in the (non-functioning) design it replaced. Its 120 copies of the same thing.

ya gotta love SMT :)



Regards, Joerg 

Cheers
Terry




You can get dumb otp uPs for under a dollar, and it usually costs more
to place cheap parts than the parts cost themselves.

John

indeed. but the total assembled PCB costs 2/3 of the design it replaced - the 3 $15 chips I replaced with $1 worth of discretes were a big saving too :)

For my next trick, I will design out the 3 legacy components, firstly the 18 $0.56 green LEDs. The customer loves the 17 $0.22 blue LEDs I put in (which sit behind a blue bit of the label, but used to be red), but I like the $0.08 red & yellow LEDs.

I especially like the photodiode that Fairchild made just for us, QSB34CGR. Y'all can buy them now too :) 



Hey, how about a photosensitive pcb-mount tamper detector? If light
ever hits the board, the warrantee is void.


often used in security systems, to detect opening the enclosure.

I toyed with the idea of hiding a photodiode under a bit of label that doesnt look like it has one, so we could use it to short SCL to 0V to easily allow a USB flash upgrade (the s/w guy hasnt figured out how to do that yet, so we use whip out the PCB and use tweezers)



product testing yesterday, IT LIVES bwahahahahaha

EMC testing tomorrow, should be a doddle (famous last words...)

Cheers
Terry



We were just discussing assembly cost with my production folks, and
decided that, on average, it's costing us something like 20 cents per
part, by the time it's all set up, placed, soldered, and inspected.
This is for modest production runs - 10 to maybe 40 boards at a whack
- of fairly dense surfmount with a few thru-hole connectors and such.

John

that sounds about right. our volumes are a lot higher, so assy cost plummets. But I am currently gearing up to do some drop tests, to try and get rid of 8 screws with large washers - the screws cost NZ$0.16 each, $0.30 assembly cost. All up four times as much as the 128-LED driver circuit.

Years back we were designing a range of motor controllers, which had to be low cost. We used an existing micro & s/w, and wrapped all new h/w around it. The original control board had about $45 worth of components, but all the fiddly screws, spacers etc. for the display & buttons (which mounted on the control card) cost $27. custom-made stuff, aaargh. Its amazing how things you dont pay attention to can sneak up and bite you.

Cheers
Terry
.

Quantcast